Structural, biological and nutritional properties of biopolymer-coated nanoliposomes containing poppy-pollen peptides prepared by two-step hydration method: Membrane stability and gastrointestinal release

Bioactive peptides (BPs), despite their multiple biological and nutritional effects, suffer from low bioavailability, instability, and high reactivity. Therefore, in this study, stabilization and preservation of the biological activities of poppy pollen peptides (PPPs) within coated Nanochitosomes (NCs) with different concentrations (0.1–0.5% w/v) of chitosan were evaluated. NCs loaded with PPPs exhibited DPPH (∼42.5%), ABTS (∼33.4%), OH (∼21.8%), and NO (∼8.9%) radical scavenging capacities. According to physical indices, stability and EE, the optimized NCs (0.3%w/v) sample showed better mean particle size (∼144 nm), homogeneity (PDI 0.25), zeta potential (∼19 mV), and encapsulation efficiency (EE ∼78%) compared to other treatments. Loading of PPPs into the inner compartment and successful adsorption of the polymer onto the external surfaces of the vesicles were confirmed by FTIR analysis. SEM, TEM, and AFM analyses indicated preserved membrane integrity, colloidal stability, and vesicle (NC) morphology. In contrast, increases in size, aggregation, particle agglomeration, and system turbidity-especially after freeze-thaw stress, were observed in NLs systems. This study also demonstrated the protective effects of the polymer coating on the controlled and targeted release of PPPs under simulated gastrointestinal conditions. These findings suggest that NCs can improve PP-derived peptide delivery and therapeutic efficacy in pharmaceutical and nutraceutical applications.